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Show 1894.] SO-CALLED S A L M O N O I D FISHES O F T H E E N G L I S H C H A L K . 655 Angora Babbit which had shed its entire coat in one piece for two years in succession. This seemed to show an analogy in a mammal to the simultaneous moulting of certain birds. Sir William Flower exhibited a specimen of a Hairy Armadillo (Tatusia pilosa), obtained by M . J. Kalinowski in the Maraynioc district of Central Peru. It had been acquired by the British Natural History Museum in exchange from the Branicki Museum, Warsaw, through the kind offices of Dr. Stolzmann. In dimensions and other characters it exactly resembled the specimen belonging to the Scarborough Museum, that Sir William Flower had brought before the Society on November 16,1886 (see P. Z. S. 1886, p. 419), which was identified with Cryptophractus pilosus of Fitzinger (32te Versamml. deutsch. Naturf. u. Aerzte, 1856, Tageblatt No. 6, S. 123), and with Praopus hirsutus of Burmeister. A communication from Mr. J. T. Cunningham treated of the significance of diagnostic characters in the Pleuronectidse. In this paper the specific and generic characters of the so-called Top-knot (Zeugopterus) were first considered. The principal generic characters were the perforation of the gill-septum, found also in Amoghssus megastoma, and the prolongation of the dorsal and ventral fins on to the right side at the base of the tail. The marked peculiarity of habit was that of adhering to vertical surfaces. It was shown that this was independent of either of the characters mentioned, and was due to the pumping-action of the longitudinal fins and their muscles posteriorly, the enlargement of these parts being also a generic character. No evidence of the utility of the specific characters could be discovered. The characters of other Pleuronectidas were similarly examined, and the conclusion reached was that there are two kinds of characters, the adaptive and the morphological. The following papers were read :- 1. A Description of the so-called Salmonoid Fishes of the English Chalk. By A. S M I T H W O O D W A R D , F.Z.S. [Received November 6, 1894.] (Plates XLII. & XLIII.) . It is remarkable that among British fossils many of the commonest and most typical species have been the least satisfactorily studied and "described. Among fishes this is more especially the case, and none have received less attention than those of the English Chalk. Some of them, such as the so-called |